1. Field of the Invention
The present invention relates to a reclining mechanism for a vehicle seat for adjusting an inclined angle of a back rest relative to a seat cushion of the vehicle seat.
2. Description of the Prior Art
There has been proposed a reclining mechanism of the type which includes a pair of attachment members respectively mounted to a frame structure of a seat cushion and to a frame structure of a back rest, the attachment members being coupled with each other and connected by means of a hinge pin for relative rotation about the hinge pin, a slide pawl slidably mounted within one of the attachment members to be moved toward and away from a ratchet portion formed on an inner periphery of the other of the attachment members, and a cam element mounted on the hinge pin and being engaged with the slide pawl for maintaining it in engagement with the ratchet portion of the attachment member and for disengaging the slide pawl from the ratchet portion of the attachment member when it is displaced by rotation of the hinge pin. In the reclining mechanism, the relative rotation of the attachment members is restricted by engagement of the slide pawl with the ratchet portion to lock the back rest at an inclined angle and is permitted by disengagement of the slide pawl from the ratchet portion for adjustment of the inclined angle of the back rest.
In the reclining mechanism, an annular bracket is coupled with outer peripheries of the attachment members and caulked thereto to assemble the component parts of the reclining mechanism as a unit. However, use of the annular bracket results in an increase of weight and size of the reclining mechanism, and the caulking process of the annular bracket is complicated, resulting an increase of the manufacturing cost of the reclining mechanism.
It is, therefore, a primary object of the present invention to provide a reclining mechanism the component parts of which are assembled as a unit without using any other bracket so that the reclining mechanism can be manufactured in a small size at a low cost.
Another object of the present invention is to provide a reclining mechanism wherein the frame structure of the seat cushion or the back rest is utilized to assemble the component parts of the reclining mechanism as a unit without using any other bracket.
According to an aspect of the present invention, there is provided a reclining mechanism for a vehicle seat which comprises a first attachment member mounted to a frame structure of a seat cushion or a back rest of the vehicle seat, a second attachment member mounted to a frame structure of the other of the back rest or the seat cushion, the attachment members being coupled with each other at their outer peripheries and connected by means of a hinge pin for relative rotation about the hinge pin, a slide pawl slidably mounted within one of the attachment members to be moved toward and away from a ratchet portion formed on an inner periphery of the other of the attachment members, and a cam element mounted on the hinge pin in a space between the attachment members and being engaged with the slide pawl for maintaining it in engagement with the ratchet portion of the attachment member when the hinge pin is retained in position under load of a torsion spring assembled thereon and for disengaging the slide pawl from the ratchet portion of the attachment member when the hinge pin is rotated against the load of the torsion spring, wherein either the frame structure of the seat cushion or the frame structure of the back rest has a support portion formed with an annular recess for engagement with the outer peripheries of the attachment members, and wherein the attachment members are assembled as a unit by engagement with the annular recess of the support portion of the frame structure at their outer peripheries.
According to another aspect of the present invention, there is provided a reclining mechanism for a vehicle seat which comprises a first attachment member mounted to a frame structure of a seat cushion or a back rest of the vehicle seat, a second attachment member mounted to a frame structure of the other of the back rest or the seat cushion, the attachment members being coupled with each other at their outer peripheries and connected by means of a hinge pin for relative rotation about the hinge pin, a slide pawl slidably mounted within one of the attachment members to be moved toward and away from a ratchet portion formed on an inner periphery of the other of the attachment members, and a cam element mounted on the hinge pin in a space between the attachment members and being engaged with the slide pawl for maintaining it in engagement with the ratchet portion of the attachment member when the hinge pin is retained in position under load of a torsion spring assembled thereon and for disengaging the slide pawl from the ratchet portion of the attachment member when the hinge pin is rotated against the load of the torsion spring, wherein one of the attachment members has an outer peripheral portion formed with a projection which is deformed radially inwardly by caulking and engaged with the outer periphery of the other of the attachment members to assemble the attachment members as a unit.
In the reclining mechanism, it is preferable that the attachment members each are in the form of a disk member and that one of the attachment members has an outer peripheral portion formed with a plurality of circumferentially spaced semi-circular projections which are deformed radially inwardly by caulking and engaged with the outer periphery of the other of the attachment members to assemble the attachment members as a unit. Alternatively, the projection formed on the outer periphery of one of the attachment members is punched at its inside end face and deformed radially inwardly for engagement with the outer periphery of the other of the attachment members.
According to a further aspect of the present invention, there is provided a reclining mechanism for a vehicle seat which comprises a first attachment member mounted to a frame structure of a seat cushion or a back rest of the vehicle seat, a second attachment member mounted to a frame structure of the other of the back rest or the seat cushion, the attachment members being coupled with each other at their outer peripheries and connected by means of a hinge pin for relative rotation about the hinge pin, a slide pawl slidably mounted within one of the attachment members to be moved toward and away from a ratchet portion formed on an inner periphery of the other of the attachment members, and a cam element mounted on the hinge pin in a space between the attachment members and being engaged with the slide pawl for maintaining it in engagement with the ratchet portion of the attachment member when the hinge pin is retained in position under load of a torsion spring assembled thereon and for disengaging the slide pawl from the ratchet portion of the attachment member when the hinge pin is rotated against the load of the torsion spring, wherein either the frame structure of the seat cushion or the frame structure of the back rest is formed with a pair of spaced support lugs which are deformed radially inwardly by caulking and engaged with an outer periphery of one of the attachment members to assemble the attachment members as a unit.
According to another aspect of the present invention, there is provided a reclining mechanism for a vehicle seat which comprises a first attachment member mounted to a frame structure of a seat cushion or a back rest of the vehicle seat, a second attachment member mounted to a frame structure of the other of the back rest or the seat cushion, the attachment members being coupled with each other at their outer peripheries and connected by means of a hinge pin for relative rotation about the hinge pin, a slide pawl slidably mounted within one of the attachment members to be moved toward and away from a ratchet portion formed on an inner periphery of the other of the attachment members, and a cam element mounted on the hinge pin in a space between the attachment members and being engaged with the slide pawl for maintaining it in engagement with the ratchet portion of the attachment member when the hinge pin is retained in position under load of a torsion spring assembled thereon and for disengaging the slide pawl from the ratchet portion of the attachment member when the hinge pin is rotated against the load of the torsion spring, wherein a thrust member is coupled with one of the attachment members and welded to the frame structure of the back rest or the cushion seat to assemble the attachment members as a unit.